Mining shield



Dec. 31, 1963 JOSEPH 3,115,754

MINING SHIELD 6 Sheets-Sheet 1 INVENTOR. 1905 D. Jose ob,

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Dec. 31, 1963 R. D. JOSEPH 3,115,754

MINING SHIELD Filed Jan. 25, 1959 6 Sheets-Sheet 2 INVENfOR, Ray D. Jose obi dj ofnefJ Dec. 31, 1963 v JQSEPH 3,115,754

MINING SHIELD Filed Jan. 2:, 1959 e Sheets-Sheet a 3 f I \J\\ l/ I a a 2 's H V iii" W l l .20 L.) i L 7 w a o INVENTOR. Roy D. Jose oh.

Dec. 31, 1963' R. D. JOSEPH- 3,115,754

MINING SHIELD Filed Jan. 23, 1959 6 SM 4 INVENTO Ray D. Joac p Dec. 31, 1963 R. D. JOSEPH 3,115,754

-' MINING SHIELD Filed Jan. 23. 1959 e' SHeets-Sheet 5 INVENTOR.

Dec. 31, 1963 R. D. JOSEPH I 3,115,754

MINING SHIELD Filed Jam 23, 1959 6 Sheets-Sheet 6 W W g B Film o o o o INVENTOR. Pay 0. Joseph. Fl 1 I BY W flzflfiguz Alla-nap United States Patent 3,115,754 MINING SHIELD Roy D. Joseph, Pittsburgh, Pa; Hazel V. Joseph, executrix of said Roy D. Joseph, deceased, assignor to Dowty Mining Equipment Limited, Ashchurch, Tewkesbury,

Glos, England, a company of Great Britain Filed Jan. 23, 1959, Ser. No. 788,551 6 Claims. (Cl. 6145) This invention relates to apparatus for the purpose of supporting the roofs of under-ground excavations, such as the roof of a coal or mineral mine, and tunnels driven into ground strata. It is desired for the purpose of giving protection to workers and equipment, against material which falls from the roof and sides of the excavation.

The need for greater safety and continued protection to the lives of Workers and high priced mechanized units, against falling rocks and other debris from under-ground excavations, is presently causing great concern. Roof falls have been one of the major mine hazards and are now the predominant cause of injuries and death in the bituminous and anthracite coal industries; a large percentage of these accidents happening within short dis tances of the coal face being worked. It is a known fact that the introduction and use of mechanical loading and continuous mining has brought about a concentration of mining which multiplies hazards incident to falling coal, rocks and other debris. It is therefore a purpose of the present invention to provide shielding means which will give overall protection against roof falls within a reasonable distance of the working faces of underground excavations, and to provide temporary and effective support during the cutting, shooting, loading and supporting cycles of operation, as well as to provide effective roofing support during continuous mining operations.

A further object of this invention is to provide an improved roof supporting shield assemblage of such nature that the same can be used at the face of under-ground operations without interference with operators and the operation of mining or excavating equipment, and which assemblage can be timed and synchronized with the movements of workmen and equipment.

A further object of this invention is the provision of a shield for protection against falling materials incident to under-ground operations, adapted to be located at the face of operations, and comprising a plurality of articulated or segmented and mated frame units which can be manipulated for the purpose of facile advancement as the excavation proceeds, with a high degree of safety to operators and excavating equipment.

A further object of this invention is the provision of a readily maneuvera-ble multiple unit roof supporting shield including a plurality of units adapted for use in connec tion with under-ground excavations, at the site or face of excavation, with means by which the shield units can be expeditiously advanced both, linearly in both direct-ions, and laterally, or obliquely, depending upon the direction of excavation. Oblique movement is important, because the shield units can be used for excavating crossways, as in a coal mine. It is at the mining of crossways, between main passages, where most casualties occur, due to roof fall. Since the shield units angle with respect to each other to permit advancement crosswise as well as linearly, they can be advanced in the desired direction for safely supporting overhead roofing against collapse.

A further object of this invention is the provision of an improved roof support for use in connection with under-ground excavations which will conform to certain undulations and irregularities of roof and flooring surfaces of the passage being excavated.

3,115,754 Patented Dec. 31, 1963 A further object of this invention is the provision of a collapsible mining shield for use in supporting overhead roofing during under-ground excavations which by reason of its maneuverable features can be lowered and collapsed upon conventional mine equipment and transported astride such equipment; thus eliminating the necessity of dis-assembly before, and assembly after moving.

Other objects and advantages of this invention will be apparent during the course of the following detailed description.

In the accompanying drawings, [forming a part of this specification, and wherein similar reference characters designate corresponding parts throughout the several views:

FIGURE 1 is a plan view of the shield assemblage showing a plurality of interlocked units in their extended positions, and also showing lateral bars and advancing and retracting hydraulically actuated rams which control the relative position of the units.

FIGURE 2 is a front elevational view of the shield assemblage, looking in the direction of the excavation face from the position shown by lines 22 of FIGURE 1, and showing the clearance passage which will enable operators and mining equipment to occupy the shaft or under-ground passage being excavated, Without hindrance.

FIGURE 3 is a plan view of the mining shield assemblage showing the interlocking units collapsed, and in dot and dash lines showing the manner in which the roof supporting units may be obliquely or angularly disposed, as would be the case when it is desired to laterally direct the excavating line to mine or excavate a cross passageway.

FIGURE 4 is a side elevational view of the shield assemblage units, showing them in collapsed or retrieved relation, and in dot and dash lines showing the front unit projected into extreme forward position to a location adjacent the face of excavation.

FIGURE 5 is an enlarged cross sectional view taken substantially on the line 55 of FIGURE 3, and more particularly showing the clamps or connecting means by which the lateral bars or beams are detachably connected to the longitudinal bars or beams, and in dot and dash lines showing one of the longitudinal beams in a lowered non-roof supporting position.

FIGURE 6 is a fragmentary enlarged cross sectional view taken through .the units of the shield assemblage, and showing clamping and connecting details; the view being taken substantially on the line 66 of FIGURE 1.

FIGURE 7 is a fragmentary front elevational view of one type of clamp which may be used to connect the lateral and longitudinal beams or bar members.

FIGURE 8 is a fragmentary perspective view, partly in section, showing the manner in which the jacks of the assemblage may be connected to the lateral bars or beams of a roof supporting unit.

FIGURE 9 is a fragmentary view showing clamping means used to detachably' connect one of the side bars of a unit to a vertical support, such as a jack leg as more particularly shown in FIGURE 10.

FIGURE '10 is a fragmentary perspective developed view, showing the manner in which various types of clamps are used to connect lateral and longitudinal beams or bars with respect to each other, and with respect to a jack, and furthermore showing in developed perspective, the manner in which a side beam may be clamped to a jack leg.

FIGURE 11 is a perspective View of one form of roof clamp which may be used in the position shown upon a lateral bar or beam for clamping a longitudinal bar or beam; the longitudinal bar or beam not being shown.

FIGURE 12 is a perspective view of the clamp and beam of FIGURE 11 with the clamp in inverted position such as would be the case where the longitudinal bar is to be attached vertically closer to the lateral bar or beam.

FIGURE 13 is a cross sectional view taken through one of the hydraulic jacks or legs, showing the valves and other details.

FIGURE '14 is a diagrammatic view showing the hydraulic system and control means for actuating the various hydraulic jacks and rams.

FIGURE 15 is a plan view of a form of shield assemblage which is pnovided with collapsible lateral beams or bars, showing rams for extending and collapsing the sections of said lateral beams or bars.

FIGURE 16 is an enlarged fragmentary cross sectional view taken through the lateral bar of the shield of FIG- URE 15; the 'view being taken substantially on the line 1616 of FIGURE 15, and the parts of the bar being shown in extended relation.

FIGURE 17 is a fragmentary cross sectional view showing the details of FIGURE 16, but with the beam sections or parts collapsed.

'FIGURE 18 is a fragmentary side elevational view showing the shielding assemblage of FIGURE 15 with the lateral bars collapsed, and more particularly also showing the relation of the longitudinal beams, hydraulic rams to cause the collapsing, and the hydraulic jacks.

FIGURE :19 is an end view of the shielding assemblage shown in FIGURE 15 looking in the direction of the line 19- 19 shown adjacent to FIGURE 15.

FIGURE 20 is an enlarged fragmentary cross sectional view taken substantially on the line 20--20' of FIGURE 18, and more particularly showing one of the clamps for connecting one of the collapsible parts or sections of the collapsible lateral bars, and the means by which it is attached to a longitudinal bar of a shield unit.

FIGURE 21 is a fragmentary perspective view partly in section, showing a detachable clamping means for connecting a ram to the adjacent jack structures of the longitudinally collapsed units of the shielding assemblage shown in FIGURE 15, when it is desired'to position the rams for laterally collapsing of the lateral bars or beams.

In the drawings wherein are shown preferred and modified constructions of the improved shielding assemblage, the letter A generally designates the shielding assemblage which principally consists of articulated front and rear frame units B and C. Hydraulic jacks or props D are provided at each corner of each of the units B and C for vertically raising and lowering the roof supporting structure of the units. Hydraulic rams E are provided for the purpose of advancing and retracting the units B and C with respect to each other, and means and a system F is provided to actuate the hydraulic jacks D and the rams E for the purpose of manipulating the various parts of the shielding assemblage. A modified form of collapsible assemblage G is provided, in which the frame units B and C areeach laterally collapsible, and in which case hydraulic rams E are used for such purpose.

Attention is called to the fact that the various parts of the units B and C are detachable with respect to each other, and the jacks D and rams E are also detachable with respect to their frame units. This is for the purpose of providing an assemblage which is completely demountable and can be compacted into a relatively small storage space. The shielding assemblage has a high degree of portability both longitudinally and laterally within a shaft or passageway being excavated.

The frame units B and C are almost identically formed, each consisting of front and rear lateral beams or bars 30 and 3 1 respectively which are connected together by means of longitudinal bars or beams 32. The lateral bars or beams 34 and 31, as well as longitudinal beams 32, are preferably of fabricated metal, having a substantially square or rectangular cross section, and being tubular. It is shown in various views that each of these bars 30*, 31 and 32 includes a top horizontal wall 34; vertical l spaced walls 35 had 36 which at their lower edges are in- Wardly flanged at 37; the flanges being in spaced relation at their facing edges. The longitudinal bars 32 at their ends are bevelled and preferably closed by plates 38, such as shown in FIGURE 10 of the drawings for the longitudinal bar 32.

The longitudinal bars or beams 32 are evenly spaced upon the lateral bars 39 and 31 of the respective units B and C; the spacing being important because the units B and C are interlocked, as shown in the drawings, so that the foremost lateral beam 3% of the unit C lies between the lateral beams or bars 3t) and 31 of the unit B, and likewise the rearmost lateral beam or bar 31 of the unit B lies between the lateral beams 30 and 3d of the rear unit C. The longitudinal bars or beams 32 of the unit B are staggered with respect to the longitudinal beams or bars 32 of the unit C; lying midway in these spaces, whereby the roof supporting portions of the units B and C consisting of the beams 3t), 31 and 32 may be longitudinally collapsed into the full line positions shown in FIGURE 3, or extended into the position shown in FIGURE 1. Likewise, the space widths between the longitudinal bars are such as to permit the angling of the units B and C, as is shown in the dot and dash lines of FIGURE 3, as would be the case when it is desired to laterally deflect the line or curve of the passageway being excavated. This would be the case in excavating cross-ways between the main tunnels or shafts of coal mines, etc.

The ends of the longitudinal beams or bars 3-2 lie uppermost upon their (respective lateral beams or bars 3% and 3 1 and they are detachably connected thereto by means of invertible or reversible clamp structures 4% to be subsequently described. The longitudinal and lateral beams of each unit B and C comprises an overhead roof supporting means, top or section.

Each jack prop structure D, as more particularly detailed in FIGURES 10, 13 and 14 preferably comprises the leg or casing 4-1 having a base or foot 42. The leg 411 is cylindrical in shape and intermediate the ends may have a cylinder supporting disc 43 adapted to support a detachable cylinder 44 which is removable from the passageway 45 of the leg 41 above the disc 4-5.. The cylinder 44 slidably fits in the passageway 4-5 and it receives therein a slidable piston 46 best shown in the diagrammatic view of FIGURE 14, to which is attached a piston rod 4 7 which extends upwardly and is provided with a beam mounting block '48 for detachable connection with the lateral beams or bars 30 and 31. The hydraulic cylinders 44 including their piston and piston rod mechanisms are double acting, and below the piston 46 upon the cylinder -44 is located a valve 49 and above the piston 46 is also located a valve 54 It will be noted from FIGURE 13 that the leg casing 41 is slotted at 51 to enable the cylinder studs which receive the valves 49 and St} to slide therealong in order to permit detachment of the cylinder 44 from the jack leg 4 1.

The seating block 4 8 fixedly secured to the upper end of the piston rod 47 of each jack D is of general U-shaped formation, including a channel-way 54 adapted to receive the lateral bar 30* or 31 therein, as is shown in various drawings; the dis-assembled position being shown in the developed view of FIGURE -'10. The ends of the lateral bars 30 and 31 which seat in the blocks 48 are provided with openings 55 therein and the upstanding walls of the channel-shaped seating block 4 3 are similarly provided with mating openings 56. When the beams lie in the seating blocks, these openings 55 and 56 align and are adapted to receive headed split shank type pins 57. These pins are used upon the equipment of this invention for the purpose of detachably connecting various parts so that may be readily assembled and dis-assembled. The pins 57 are headed and their shanks are split and laterally flexible; the ends opposite the heads being tapered as shown at 58 in FIGURE 10 of the drawing to facilitate insertion of the same in the aligning openings 55 and 56; the pin 57 between the tapered end 56 and the head 59 being laterally enlarged at 60, at the locus of lateral flexibility, to enable a wedge-like action in frictionally holding the pin-s in place upon the units with which they are engaged.

Referring to the connectors or clamps 40, each of the same includes complementary beam encompassing portions 60 and 61; the portion 60 being U-shaped in formation, as shown in FIGURE and adapted to straddle a lateral beam 30 or 31, as the case may be. The portions 60 and 61 inter-fit; a leg of the beam straddling portion 60 being provided with an opening 62 therein into which an end 63 of the portion 61 fits in order to rest upon the lateral flange 61 forming part of the portion 60. At the opposite side, portion 60 is provided with spaced tongues 63 the ends of which are curved at 64 to provide a seat for a pin 57; the spacing of the tongues being such that the portion 61 will fit into the space; the upper end of the portion 61 having a complementary curved portion 65 which defines with the curved portions 64 a passage to receive one of the split pins 57 by which the portions 60 and 61 may be clamped together in encompassing relation about the beam 39 or 31. The portion 60 of each clamp 40 is provided with a pair of integral relatively spaced attaching legs 66 and 67, each provided with openings 70 and 71 therein; the openings 76 aligning, as do also the openings 71. The longitudinal beams 32 are provided with integral lugs 73 (see FIG. 10) in downwardly facing relation thereon at the ends thereof, transversely apertured at 74, and which apertures are adapted to align with the openings 70 or 71 to receive a pin 57. In the case of the uppermost clamp 40 shown in FIGURE 10 the pin 57 will extend through openings 70. The clamp 40 may be inverted so that the lug 73 fits between the legs 66 and 67 in aligning relation with the openings 71 to receive a pin 57.

It is shown in FIGURE 4 of the drawings that the longitudinal bars 32 of the unit B are secured at their forward ends to the most advanced lateral bar 30 by the clamps 40 in the position shown by the clamp 40 in FIGURE 12, and the opposite end of each bar or beam 32 is secured to the lateral beam 31 of the unit B with the clamps 40 as shown in FIGURE 11. This locates the rear ends of the longitudinal beams 32 of the uni-t B on the rear lateral beam 31 at an elevation higher above the beams 31 than the fore ends of the beams 32 rests with respect to the most advanced lateral beams 30. The connections of the beams 32 of the unit C are reversed. In other words, the longitudinal beams 32 of the unit C at the rearmost lateral beam 31 are secured by the clamps 40 in the position shown at the left in FIG. 6, and the most forward ends of these beams 32 of the unit C are secured to the second to foremost lateral beam 30 with the clamps in the position shown to the right in FIG. 6. It will be noted that through manipulation of the jacks D, the top surfaces of the longitudinal beams 32 of the unit B may be lowered below the top surfaces of the longitudinal beams 32 of the unit C, as is shown in FIGURE 4, and likewise the condition can be reversed, in that the beams 32 of the unit C can be made to lie at their top surfaces below the plane in which the top surfaces of the beams 32. of the unit B lie. This enables facile manipulation of the units B and C, so that one or the other may be advanced or retracted in the excavated passageway or tunnel. The sectional view of FIGURE 5, taken on the line 55 of FIGURE 3, shows the clamp 40 of the extreme right lateral beam 30 of unit B is connected upon the longitudinal beam 32 by means of the clamp and its pin 57, with the latter extending through the openings 71, and it is shown in the same view that the adjacent rear lateral beam 30 of the unit 0 is connected by means of its clamp 40 with the pin 57 extended through the openings 70. The two clamps 40 shown in FIGURE 5 are thus relatively inverted.

Because of the offset condition in which the clamps 40 may be connected to the lateral bars 30 and 31, the longitudinal beams at one end are each connected closer to its adjacent lateral beam than the opposite ends of said longitudinal beams are connected to their adjacent lateral beam. This renders it possible to elevate and lower the two units B and C with respect to each other, through manipulation of the jacks D.

At the sides of each of the units B and C, the two jacks for each of the units B and C are connected by means of low positioned side beams 80. Special clamps 81 are provided for clamping the ends of these side beams or bars to the complementary jacks at the sides of each of the units B and C. These clamps 81 each consists of complementary segments 82 and 83 which are adapted to inter-engage much the same as the sections 60 and 61 of the clamps 40; the segments 82 having spaced legs 84 apertured at 85 to receive a pin 57 shown in FIGURE 7; each end of the side bar 80 being provided with a transversely apertured lug 86 adapted to interfit between the legs 84 to receive a pin 57. Furthermore, the tongue ends of the segments 82 and 83 (see FIGURE 10) are curved in a manner similar to that above described for the clamps 40 to receive the pins 57, shown in FIGURE 10, by means of which the segments of the clamps 81 may be secured around the leg of the jack D. It is shown in FIGURE 4 that these side beams 80 of the units B and C are offset vertically with respect to each other; the beam 80 for the jacks D of the unit C being located above the side beam 80 connected to the jacks D of the unit B.

Referring to the hydraulic ram structures E, and more particularly referring to FIGURES l, 3 and 6 of the drawings, ram structures E each includes a cylinder section 90, which as is shown in the diagrammatic view of FIGURE 14 is provided with a piston 91 operating therein to which is connected a piston rod 92. As is shown in FIGURE 6 of the drawings, one of the clamps at) is detachably connected to the lateral beam 31 of the unit C in the position of the clamp shown in FIGURE 12, and likewise a clamp 40 is connected to the lateral beam 30 of the unit B in the same position. The piston rod 92 is connected by one of the pins 57 to an offset end 94 upon the end of the piston rod 92, and the cylinder 90, :at its remote end, has an offset 95 which is connected by a pin 57 to the lowermost openings 70 in the clamp legs 66 and 67. This positions the ram; both cylinder and piston rod, at a location between the beams 30 and 31 of the units C and B respectively in such close relation to the roof supporting bars 32 that there will be no interference, so far as clearances are concerned, to efficient mining operations. In FIGURES 1 and 3, it is shown that the rams E are relatively reversed. However, they need not be reversed. It is readily apparent that rams can extend the units B and C with respect to each other or retract them, since the rams are double acting, each having opposite cylinder inlets and outlets at opposite sides of the piston 91 (see FIGURE 14).

Referring to the control means F for actuation of the jacks D and hydraulic rams E, as shown in FIGURE 14; a fluid reservoir 106 is provided as is also a motor pump unit 105. Valves 107 and 108 are provided for actuating one of each of the ram units E; the valves being manually operable so that the flow of fluid through the lines shown in FIGURE 4 will be transmitted into or out of each of the end connections 106' for the purpose of moving the pistons 91 back and forth in the cylinders 90, and thus extending or retracting the units B and In FIGURE 14 is shown an upper set of four jacks D and a lower set of four jacks D. The upper set of jacks D are connected to the four corners of the unit B for actuating the same and the four jacks of the lower set D are connected to the four jacks at the corners of the other unit C, as can well be understood. It should be borne in mind that each cylinder '44 of the jack unit S" is provided with valves 49 and St at opposite sides of the piston 46 of the .jack. If now it is intended to use the upper set of jacks D for operating the unit B, the valves 49 and 50 are opened for that set of jacks, and the valves 49 and 50 of the lower set of jacks for the unit C are closed. Valves 115 and 116 are provided for directing the flow of fluid from the motor purnp 185 to the jack structures and for likewise returning the fluid to the reservoir 1%. The valve 115 is used for manual control of the jack-s D of the upper set of jacks for the unit B. The valve 116 is used to control the flow of fluid to and from the lower set of jacks D for the unit C. It will be readily apparent that the jacks D of either of the units B or C may be extended or retracted independent of the jacks of the other unit, in order to position the unit B and C for maneuvering or root support in the exavated tunnel.

The mode of initial assemblage of the various parts of the units B and C may vary. Ordinarily the hydraulic jacks are properly positioned in the first instance in rectangular arrangement, and the lateral bars 30 and 31 are then attached in the manner above described, upon the tops of the jacks by the pins 57 above described. While the drawings show only four longitudinal bars 32 for the section C and five longitudinal bars 32 for the section B, the number may vary depending upon the desired spacing between the bars in order to suit the size of the units and the conditions under which they are being used, and to afford that degree of angularity between the units to enable lateral tunneling. The units B and C are assembled and interlocked in the manner shown in the drawings and as above described and thereafter the rams E are attached in the manner above described. The assembly is completed by attaching the hydraulic power lines in the set-up shown diagrammatically in FIGURE 14.

Assuming the shield assembly A to be installed at the advancing end of the mine drift, tunnel or entry; the shield would be in the roof supporting position shown in full lines in FIGURES 1 and 2.

From the foregoing description, it is apparent that the units B and C are telescopically connected and may be manipulated so as to advance the foremost sections B as coal or excavation is removed, by means of the rams E; thus forcing the front section into the newly excavated area. During this procedure the rear section C is in roof supporting position. As the tunnel is extended, the rear section B may be retracted under section C by means of the hydraulic rams E and permanent supports, such as root bolts, may be installed. This may be done through the openings between the supporting beams of the sections or timber may be installed back of the shield A as the rear section is advanced Lateral collapse of the modified form of shield G from the position shown in FIGURE to the position shown in FIGURE 18 may be accomplished as shown in the various views FIGURES 15 to 21 inclusive. Such lateral collapse will be desirable in connection with moving or transporting the shield assemblage bodily. The units B and C are constructed, as to longitudinal main beams 32*, jacks, etc., the same as for the shield assemblage A set forth in the above description. However, the difference in the laterally collapsible shield G is that the lateral beams 30* and 31 of the units B and C are extensible and retractible between the positions shown in FIGURES 15 and 18 of the drawings. Thus, each of the beams 30* and 3 1 of the units B and C preferably consists of hollow end sections 136 and 131 which may be designated as stub sections, and an intermediate or saddle bar tubular section 132 into which the adjacent ends of the sections 130 and 131 are telescoped. Each intermediate saddle bar section 132 at the ends thereof is provided with retaining lips or flanges 135 extending into the passageways of the sections of the collapsible parts of the lateral bars, and likewise complementary lips or fiagcs 136 are provided on the inner ends of the sections 1313 and 131.

These lips or flange extensions and 136 permit the stub ends 133 and 131 to extend outwardly from the saddle bar section 132 to the position shown in FIG- URE 16, at which time the bars 38 and 31 are fully extended or the stub bars 138? and 131 may be collapsed into the saddle bar section 132 into the position shown in section in FIGURE 17, and in end elevation in FIG- URE 18.

The hydraulic rams E, which are of the same construction as the hydraulic rams E above described, may be used to collapse the sections of the lateral bars Sit and 31. If it is desired to laterally collapse the shield assemblage G, the two sections B and C are longitudinally collapsed into the position shown in FIGURE 15, and at which time the jacks D at each corner of the collapsed assembly will assume the positions shown in FIGURES 15 and 21 of the drawings. A clamp 140' shown in FIG- URE 21 consists of an elongated end curved section 141 which is welded at 142 to an inverted channel seat 143 adapted to be connected by one of the pins 57 to an end of either the piston or cylinder of the ram E; FIG- URE 21 showing the pin 57 connecting the piston end of ram E. A complementary clamp portion 144 may be connected by one of the pins 57 to the top of the channel seat 143; the sections 141 and 144 thus engaging upon and in grooves 145 provided in the top ends of the piston structures of the jacks D, as shown in FIGURE 21. This arrangement will detachably connect the pair of jacks D at each corner of the collapsed assemblage as shown in FIGURE 15, to the hydraulic ram construction E in order that through control of the hydraulic fluid in the ram, which is double acting, the same is the ram E above described, the lateral beams 30* and 31 may be collapsed or extended at will.

From the foregoing, it will be noted that the two units B and C, which are polygonal shaped in plan and which only have jack props at each corner, are so interengaged and associated that While they may be advanced and retracted, they cannot be separated from each other. Thus, anything under the canopy roof engaging bars is afforded protection against falling roof materials such as would be likely to injure the operating personnel. Furthermore, in the shield assemblage, one unit when it moves is supported upon and by the other unit and during such movement the jack props are normally supported clear of the rock or floor surface. Another advantage of the assemblage is that when drivage has reached the point where the coal has been extracted the shield can be collapsed and positioned upon a continuous mine or shuttle car or other convenient machinery and moved to the next drivage without any dis-assemblage of the two units.

Various changes in the shape, size and arrangement of parts may be made to the form of invention herein shown and described, without departing from the spirit of the invention or scope of the claims.

I claim:

1. A shield for supporting the roofs of underground tunnels comprising a plurality of cage type roof supporting units having means connecting them against relative detachment for relative advancement and retraction and oblique angling with respect to each other, power means for independently elevating and lowering said units whereby-either of the units may support a roof while the other is lowered and released from root support, and power actuated hydraulic ram means for longitudinally advancing and retracting the units withrespect to each other, and laterally obliquely angling of the same with respect to each other.

2. In a mine shield assemblage for supporting mine root's and like roof structures, the combination of a plurality of units each of which comprises a roof supporting section consisting of relatively spaced lateral supporting beams and a plurality of longitudinal beams, means connecting similar ends of each of the longitudinal beams of each unit to one of the lateral beams of that unit, means connecting the other ends of the longitudinal beams of that unit to another lateral beam of the same unit, the last mentioned connecting means of each unit spacing the roof supporting surfaces of its longitudinal beams farther away from the respective lateral beam to which connected than the roof supporting surfaces of the other ends of said last mentioned longitudinal beams are spaced with respect to the lateral beam to which said last mentioned ends are connected, said roof supporting sections being interconnected with the lateral beams which are farthest spaced from the roof supporting surfaces of the respective longitudinal beams to which connected lying between the lateral beams of the other unit and with the longitudinal beams of the two units relatively spaced and staggered with respect to each other so that the longitudinal beams of each unit which lie above a lateral beam of the other unit may rest thereon and also be raised therefrom, power actuated jack props connected to the ends of each of the lateral beams of each unit, and power actuated means connecting the units for the purpose of relatively longitudinally moving them with respect to each other.

3. A mine shield assemblage as described in claim 2 in which the connections of the longitudinal beams upon the lateral beams of each of the units are detachable, and in which the connections of the power actuated props at the ends of the lateral beams are detachable with respect to said lateral beams, and in which the power actuated means connecting the two units for relative longitudinal movement have detachable connections with said units.

4. In a mine shield for supporting the roofs of underground tunnels, the combination of a plurality of roof supporting units each of which includes relatively spaced lateral beams and longitudinal roof supporting beams connected in relatively spaced relation rigidly upon the lateral beams of each unit, with the longitudinal beams of one unit being spaced between the longitudinal beams of the other unit and with the units having a lateral beam of each movably interconnected between the lateral beams of the other unit whereby the units may be moved into advanced or retracted relation, power actuated jack props connected to the lateral beams of each unit at the ends thereof, the lateral and longitudinal beams being so constructed and arranged that when the jack props of one unit are retracted the longitudinal beams of that section will slidably rest upon the lateral beams of the other unit which lies between the lateral beams of the other unit whereby to support the unit with the jack props retracted so that the latter unit may be advanced or retracted with respect to the other unit, the lateral beams being of rigid construction from end to end and each of them being formed of telescopically extensible and retractable sections.

5. In a mine shield assemblage for supporting mine roofs and like roof structures, the combination of a plurality of units each of which includes a roof supporting section comprising spaced lateral supporting beams and a plurality of relatively spaced longitudinally beams rigidly connected at their ends upon the tops of the lateral supporting beams and projecting thereabove and also extending crosswise with respect thereto, said roof sections of the two units being interconnected so that one lateral supporting beam of each unit lies between the lateral supporting beams of the other unit with the longitudinal beams of each unit slidably overlying that lateral beam of the other unit which lies between the two lateral beams of said other unit, the longitudinal beams of each unit being located in the spaces between the longitudinal beams of the other unit so that the two units may be relatively moved for linear extension and retraction and laterally moved angularly with respect to each other, and elevating and lowering power jack means at the ends of the lateral beams of each unit, the spaces below said roof sections being unobstructed so as to permit free passage of personnel and mining equipment longitudinally therethrough, and power actuating means connecting the two units to enable their longitudinal extension and retraction and lateral angling.

6. In a mine shield assemblage for supporting mine roofs and like roof structures, the combination of a plurality of units each of which includes a roof supporting section comprising spaced lateral supporting beams and a plurality of relatively spaced longitudinal beams rigidly connected at their ends upon the tops of the lateral supporting beams and projecting thereabove and also extending crosswise with respect thereto, said roof sections of the two units being interconnected so that one lateral supporting beam of each unit lies between the lateral supporting beams of the other unit with the longitudinal beams of each unit slidably overlying that lateral beam of the other unit which lies between the two lateral beams of said other unit, the longitudinal beams of each unit being located in the spaces between the longitudinal beams of the other unit so that the two units may be relatively moved for linear extension and retraction and laterally moved angularly with respect to each other, and elevating and lower power jack means at the ends of the lateral beams of each unit, the spaces below said roof sections being unobstructed so as to permit free passage of personnel and mining equipment longitudinally therethrough, the lateral beams of the units being each of telescopic construction to permit extensions and collapsing thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,641,906 Knights June 16, 1953 2,756,034 Calder July 24, 1956 2,795,936 Blower June 18, 1957 2,801,522 Kuhn Aug. 6, 1957 FOREIGN PATENTS 619,297 Germany Sept. 27, 1935 954,897 France June 20, 1949 816,237 Germany Oct. 8, 1951 827,051 Germany Jan. 7, 1952 759,647 Great Britain Oct. 24, 1956 

1. A SHIELD FOR SUPPORTING THE ROOFS OF UNDERGROUND TUNNELS COMPRISING A PLURALITY OF CAGE TYPE ROOF SUPPORTING UNITS HAVING MEANS CONNECTING THEM AGAINST RELATIVE DETACHMENT FOR RELATIVE ADVANCEMENT AND RETRACTION AND OBLIQUE ANGLING WITH RESPECT TO EACH OTHER, POWER MEANS FOR INDEPENDENTLY ELEVATING AND LOWERING SAID UNITS WHEREBY EITHER OF THE UNITS MAY SUPPORT A ROOF WHILE THE OTHER IS LOWERED AND RELEASED FROM ROOF SUPPORT, AND POWER ACTUATED HYDRAULIC RAM MEANS FOR LONGITUDINALLY ADVANCING AND RETRACTING THE UNITS WITH RESPECT TO EACH OTHER, AND LATERALLY OBLIQUELY ANGLING OF THE SAME WITH RESPECT TO EACH OTHER. 